Fix up the README table layout issue.
Fix up the README table layout issue.

The previous change added some new information into the middle table, which broke the table formatting (table content must be contiguous otherwise it ends up just rendering the | and ---- values as-is)

vladkol/MixedRealityToolkit-Unity,killerantz/HoloToolkit-Unity,killerantz/HoloToolkit-Unity,killerantz/HoloToolkit-Unity,vladkol/MixedRealityToolkit-Unity,vladkol/MixedRealityToolkit-Unity,DDReaper/MixedRealityToolkit-Unity,killerantz/HoloToolkit-Unity